A nonlinear intersubband polaritonic metasurface designed for difference‐frequency generation that provides a practical level of nonlinear response under continuous wave illumination is reported. An effective nonlinear susceptibility of up to 340 nm V⁻¹ is measured experimentally. Approximately 0.3% of λ = 5.4 µm photons are downconverted to λ = 12.9 µm photons at the focal spot in the experiment. This work indicates that the ultrathin metasurface devices may provide a versatile nonlinear element for frequency down‐ and upconversion in a relatively broad spectral range and without phase‐matching constrains of traditional bulk nonlinear crystals.

中文翻译：

---

极化子带间非线性超表面中的频差产生

报告了为差频产生而设计的非线性子带间极化超音速表面，该表面在连续波照射下提供了实用水平的非线性响应。通过实验测量了高达340 nm V ^-1的有效非线性磁化率。在实验中，大约0.3％的λ= 5.4 µm光子在下焦点下转换为λ= 12.9 µm光子。这项工作表明，超薄超颖表面器件可能会提供一个通用的非线性元件，以便在相对较宽的光谱范围内进行频率下变频和上变频，而没有传统体非线性晶体的相位匹配约束。